T cell-derived soluble factors which regulate antibody synthesis will be studied. Our observations on the activities, modes of action, cellular sources and functions will be confirmed and extended. Studies on the possible interactions between positive and negative regulatory factors in the control of immunoglobulin production will be initiated. The role of macrophages in the generation and/or activity of the mediators will be examined. Studies on the effects of these soluble factors and membrane-associated mediators as they relate to the function of T lymphocytes, or other lymphoid cells, in cell-mediated tumor immunity will be continued. BIBLIOGRAPHIC REFERENCES: Rubin, A.S. and G.N. Douglas. 1977. Nonspecific suppression of the initiation of the primary immune response in vitro. In Regulatory Mechanisms in Lymphocyte Activation: Proceedings of the Eleventh Leukocyte Culture Conference. Edited by D.O. Lucas. Academic Press, New York, in press. Douglas, G.N. and A.S. Rubin. 1977. Nonspecific suppression of the initiation of the immune response to a heterologous immunogen by supernatants from specifically-stimulated, primed lymphoid cells. Immunology, in press.